Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Imagine you zoomed in 1000X on some fabric. But then it turned out to be a skeleton!
Source Angelica
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Derived from a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Tile-able Dark Brown Wood Background. Feel free to use it as a background image in your designs or somewhere on the web. By the way, the color seems to be close to Coffee Brown.
Source V. Hartikainen
The original enhanced with one of Inkscapes's filters.
Source Firkin
Lovely pattern with splattered vintage speckles.
Source David Pomfret